  var code ; //在全局 定义验证码
/**
 * 生成验证码事件
 * @return
 */
function createCode()
	{ 
		code = "";
	var codeLength = 4;//验证码的长度
	var checkCode = document.getElementById("spanCode");
	var selectChar = new Array(0,1,2,3,4,5,6,7,8,9,'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');// 所有候选组成验证码的字符，当然也可以用中文的

	for(var i = 0;i < codeLength; i++ )
	{
		var charIndex = Math.floor(Math.random()*36);
		code +=selectChar[charIndex];
	}
		if(checkCode)
		{
			checkCode.className="code3";
			checkCode.innerHTML = code;
		}
}


$(function(){
	 createCode();
});


$(function(){
	$("#back").click(function(){
		
	});
});
